iOS 9 Review: An Upgrade That Will Save You Time and Battery - WSJ

"Like clockwork, mid-September arrives, we update to a promising new iOS, then … we learn to survive with a buggy, slow and battery-drained iPhone. Again and again. It would make a boring sequel to “Groundhog Day.”

Here’s the spoiler, though: The plague of miserable, repetitive upgrade cycles ends Wednesday, with the arrival of iOS 9.

Available as a free update on all recent devices going back to the iPhone 4S and iPad 2, iOS 9 is all about stability—with fewer hair-pulling bugs, slowdowns and battery problems. Apple was so adamant about making up for last year’s disastrous iOS 8 launch—the one that left some with no cellular connectivity—that it even gave fearless users the opportunity to test out the new software early and report bugs."